MANILA — A tropical storm in the Philippines cut through a swath of the main southern island of Mindanao, killing at least 103 people and burying many in remote areas by landslides and mudslides just as families were preparing for Christmas, officials said Saturday.

The storm, called Tembin, slammed into the eastern portion of Mindanao late Thursday, dumping torrential rains that unleashed floods into the next day. It was expected to blow out of the country by Monday.

Heavy rains caused the banks of the Cagayan de Oro River to overflow, forcing the evacuation of nearly 20,000 people. Streets turned into virtual rivers as rescuers plucked residents from their roofs.

In Lanao del Sur Province, Gov. Imelda Quibranza-Dimaporo said at least 39 people had drowned or were killed by mudslides. Soldiers and emergency crews rushed to the remote village in the region of Tubod to try to save lives, said Roy Secuya, a local disaster official.

“We could not reach village officials because power and communications lines have been cut by the storm,” Mr. Secuya said.

Ms. Quibranza-Dimaporo said at least 64 people were still missing on Saturday.

Rodel Maghinay, a municipal development planning officer in the town of Salvador, said at least 15 villages were engulfed by mudslides and cut off from nearby communities after a steel bridge was damaged.

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Rescuers evacuated residents during heavy flooding in Cagayan de Oro city in the Philippines on Saturday.Credit
Froilan Gallardo/Reuters

“These areas have remained isolated,” he said. “Floodwaters came as the Salug River system overflowed its banks. The water rose too fast.”

Rocks and boulders, some as big as cars, were washed down by flash floods that buried scores of wooden homes in the town of Piagapo, leaving at least 10 residents dead, the police said.

In Cagayan de Oro city, Kim Domingo, a volunteer rescuer, said her crews used lifeboats as they went house to house on Friday to save people. But others refused to leave their homes, she said.

“We tried hard to reach everyone,” Ms. Domingo said. “But there were many who opted to stay at home and waved us on to the next home where people needed us more.”

“We don’t know what had happened to them, but I hope to God they were O.K.,” she added.

Floodwaters had receded in the city by Saturday, leaving a thick sludge of mud and debris.

Tembin came days after Tropical Storm Kai-Tak caused widespread destruction in the central Philippines, killing at least 30 people and displacing more than 240,000.

The archipelagic country is hit by about 20 severe storms a year, many of them deadly. In 2003, Super Typhoon Haiyan, one of the strongest typhoons ever recorded, ravaged large parts of the central Philippines and left more than 6,300 people dead.